As the internet and computer networking continue to evolve, data transmission speeds are increasing as well as the amount of data transmitted. The increase in data traffic is occurring in Local Area Networks (LANs) based on Ethernet and other transport mechanisms such as Wide Area Networks (WANs) and Storage Area Networks (SANs) which could use Ethernet or any of a number of data transport mechanisms. Similarly, the amount of data moving through Internet Protocol (IP) based networks such as the internet continues to grow substantially.
Accordingly, users face a growing need for new ways to store and maintain their data. Today's technology offers three basic storage options: Direct Attached Storage (DAS), Network Attached Storage (NAS) and Storage Area Networks (SAN).
In its most basic form, Direct Attached Storage consists of a disk drive directly attached to a personal computer or server. One of the most common methods of transferring data between a hard drive and its associated personal computer or server is the Small Computer Systems Interface (SCSI). Other methods, such as SATA and IDE are well known.
The SCSI protocol uses commands to transfer data as blocks, which are low level, granular units used by storage devices, as opposed to LANs, which typically use file based methods for transferring data. The overall operation and an architectural description of the SCSI protocol is available from the American National Standards Institute (ANSI), the specific specification having the designation ANSI/INCITS 366-2003, titled Information Technology—SCSI Architecture Model-2 (SAM-2), herein incorporated reference, and herein referred to as the SCSI Specification.
As internet traffic and storage needs have grown, there is a growing convergence between storage devices, protocols, and IP based transport mechanisms. For example, current SCSI storage devices are designed to work over a parallel cable having a maximum cable length of 12 meters, While IP based transport mechanisms have no data transmission distance limitation.
At the present time, the storage industry and the various industry entities responsible for developing and maintaining the various Internet Protocols are working together to develop standards to enable SCSI based data transfers over the internet. Specifically, the IP Storage (IPS) Working Group of the Internet Engineering Task Force (IEF) is in the process of finalizing a specification for encapsulating SCSI commands in the known TCP/IP protocol. The Internet SCSI (iSCSI) protocol for block storage is predicated on standard Ethernet transports. The iSCSI protocol defines the rules and processes to transmit and receive block storage data over TCP/IP networks. iSCSI replaces the parallel SCSI direct cabling scheme with a network fabric. iSCSI is transport independent and will support any media that supports TCP/IP. Servers and storage devices that support iSCSI connect directly to an existing IP switch and router infrastructure. iSCSI enables SCSI-3 commands to be encapsulated in TCP packets and delivered reliability over IP networks. The iSCSI specification is complete and undergoing final ratification within the IETF. The current iSCSI specification is available from the IETF under the designation draft-ietf-ips-iscsi-20.txt, dated Jan. 19, 2003, and herein referred to as the iSCSI Specification. iSCSI network interfaces under development will be capable of transferring data over the internet in speeds approaching 20 Gbits/sec. The iSCSI protocol is just one example of a network storage protocol, which may employ the Interval Marker System and Method on the present invention, although those skilled in the art will appreciate that the method and system of the present invention is useful in any type of data transfer protocol where Interval Markers are useful or required.